1. Field of the Invention
The present invention relates to a controlling device for a quantity of fuel injection in a Diesel engine for controlling the quantity of fuel injection by means of electronic control in response to operating conditions in the engine.
2. Description of the Prior Art
The electronic control in Diesel engine is performed by such a manner that a deviation of a calculated injection timing obtained through the calculation by means of an electronic circuit on the basis of operating conditions of the engine from an actual control value of injection derived from a timer position sensor provided on an injection pump is found, and a driving output with respect to a timing control valve in the injection pump is changed on the basis of the deviation found in such that the actual injection timing comes to be close to the aforesaid calculated injection timing of fuel.
Incidentally, a real control value of injection timing cannot correctly be found in such a case where any trouble or accident takes place in a timer position sensor furnishing input information for an electronic circuit or in a timing control valve being an object to be controlled or in a like means, or such a case where an oil pressure circuit for effecting timer control becomes clogged by means of a deposit, dust or the like. In the case when such situations as mentioned above take place, contents of influence upon the engine become different in accordance with a state of injection timing immediately before these situations take place. For instance, chamber temperature exceeds the threshold limit value in the case where such a situation is on the side of an advance angle, whilst it brings about occurence of accident fire, increase in white smoke, abnormal rise of exhaust temperature which becomes a cause for damaging engine in the case where a situation is on the side of a retard angle.